See the stats for yourself.
The chances of a US citizen being killed by a terrorist refugee in an act of domestic terrorism is less than one in three BILLION.
Americans are more likely to be killed by their clothes than by a terrorist act involving immigrants to the US (any immigrants, not just refugees).
Turning away refugees has consequences. I hope we can make our decisions on this topic without being controlled by our fear.
(ETA more accurate falling-coconut related fatality statistics)